I. Field of the Invention
The present invention relates to an escapement for a conveyor.
II. Description of the Prior Art
There are many types of previously known conveyors, such as roller conveyors, in which articles may accumulate on the conveyor. These previously known conveyors typically comprise a frame defining a plane on which the articles to be conveyed are supported. These articles, furthermore, move in a predetermined direction of movement along the conveyor frame.
In many situations, it is desired to release articles for travel on the conveyor past a certain point only at predetermined intervals or when a predetermined event has occurred. In order to achieve this, there have been a number of previously known escapements which selectively prevent further travel of articles on the conveyor past the escapement.
These previously known escapements typically comprise a pin which is mounted to the conveyor frame and vertically movable between an engage position and a release position. In the engage position, a portion of the pin protrudes vertically upwardly above the conveyor plane so that articles conveyed by the conveyor abut against the stop pin. The articles are then held stationary on the conveyor by the stop pin until the stop pin is moved to its release position. In its release position, the pin is retracted below the conveyor plane on which the articles are conveyed thus releasing the article for further travel along the conveyor.
There have, however, been a number of previously known disadvantages with respect to these previously known escapements. One disadvantage of these previously known escapements is that, assuming that the escapement is in its engage position, articles traveling on the conveyor system strike the stop pin. In many cases, however, not only is the velocity of the article on the conveyor relatively high, but the articles themselves are relatively heavy. Consequently, these previously known escapements were subject to early failure and required excessive maintenance in view of the repeated impacts of the articles conveyed by the conveyor against the stop pin.
A still further disadvantage of these previously known stop pins is that the stop pins were movable in a vertical direction. Consequently, assuming that the stop pin is in its engage position and that an article is positioned against the stop pin, in order to move the stop pin to its release position, it has been previously necessary to overcome the friction between the stop pin and the article as the stop pin is moved to its lower or release position. In some cases, particularly with heavy articles, the actuator utilized to move the stop pin between its engage and release position was insufficient to overcome the friction between the stop pin and the article thereby causing a jam up on the conveyor line. The friction between the stop pin and the article also resulted in excessive wear on the stop pin due to the rubbing between the stop pin and the article as the stop pin is moved between its engage and release position.
The present invention provides an escapement for a conveyor which overcomes all of the above-mentioned disadvantages of the previously known devices.
In brief, the escapement of the present invention comprises a housing which is pivotally mounted to the conveyor frame and beneath the plane on which the articles are conveyed by the conveyor. Furthermore, this pivotal axis of the housing is perpendicular to the direction of movement of articles on the conveyor plane.
The housing includes a portion which is radially spaced from the axis of rotation of the escapement housing. A shock absorber constructed of a resilient material is then positioned in between the radially spaced housing portion and the conveyor frame.
A stop bar is then longitudinally slidably mounted to the housing and movable by a conventional actuator between a raised or engage position and a lowered or release position. In its raised or engage position, a portion of the stop bar protrudes above the conveyor plane thereby engaging and stopping articles from further travel past the stop bar on the conveyor. Conversely, in its lower or release position, the stop bar is vertically retracted relative to the housing so that the entire stop bar is positioned below the plane on which the articles on the conveyor are conveyed thereby releasing the articles for further travel on the conveyor past the stop bar.
In practice and assuming that the stop bar is in its engage position, an article conveyed by the conveyor impacts against the end of the stop bar. This, in turn, causes the housing to pivot slightly about its pivotal axis and compress the resilient shock absorber between the housing portion and the frame. By cushioning the impact of the article against the stop bar, the resilient shock absorber protects the escapement from the previously known impact forces of the prior art devices.
Additionally, the stop bar is movable along a preset longitudinal axis relative to the housing between its engage position and release position. This preset axis for the stop bar intersects the direction of movement of the articles on the conveyor in an acute angle. Thus, unlike the previously known escapements, upon retraction of the stop bar from its engage to its release position, the end of the stop bar engaging the conveyed article moves both downwardly and in the direction of movement of the articles on the conveyor line. In doing so, unlike the previously known escapements, frictional sliding engagement between the stop bar and the conveyed article is minimized if not altogether eliminated.